Wood is a widely used construction material that has many advantageous properties. However, it suffers from weaknesses such as low-dimensional stability and low durability in humid environments. These issues are associated with the porous vascular structure of wood that leads to a high water uptake capacity. This research aims to reduce the water uptake capacity of spruce wood by dip-coating samples in an aqueous colloid of silicon dioxide (SiO₂) nanoparticles. SiO₂ is a dense ceramic material with good chemical stability. It is readily available and affordable, making it an excellent candidate for this application. This study investigates the effect of SiO₂ impregnation on the physico-mechanical properties of spruce wood. Density measurements, water uptake tests, microscopy examination, thermogravimetric analysis, and dynamic mechanical analysis were conducted on non-treated and SiO₂-treated spruce wood samples. Quantitative and qualitative analyses demonstrated that SiO₂ impregnation performed under higher vacuum pressure was more effective compared to the atmospheric condition and exhibited a greater presence of SiO₂ in the wood’s vascular system. SiO₂ impregnation under vacuum pressure demonstrated an effective increase in the density of the wood. It also reduced the porosity, which led to a significant reduction in the water uptake of the spruce wood. The analysis of the wood viscoelastic properties revealed that SiO₂ impregnation under atmospheric and vacuum conditions triggered two different reinforcing mechanisms. The results showed that a significant improvement of the spruce wood storage and loss moduli could be achieved when impregnation was performed at the highest vacuum pressure of − 90 kPa.

Wood is susceptible to various degradation mechanisms when exposed to dynamic environmental conditions, including hydrolysis caused by the infiltration of water into the wood cell structure. This study aims to examine the differences between the effects of two types of accelerated aging on the long-term performance of white spruce wood samples to have a better understanding of the performance of spruce wood in real-world applications. Two separate sets of samples were employed in this experimental study. One set was placed in a hydrolytic aging chamber at 90 °C and 80% relative humidity while the other set was placed in a freeze-thaw cycling chamber with temperature variations from 25 °C to -18 °C at a rate of 6 cycles per day. The aged samples were tested at regular intervals, with a testing span of 3 months for the hydrolytically aged samples and 300 cycles for the freeze-thaw aged samples. The results obtained from characterization tests showed that both aging conditions caused a significant increase in the crystallinity index of the samples. This finding highlights the potential value of subjecting wood to these conditions as a pre-treatment to standardize crystallinity levels for experimental purposes. Ultimately, the hydrolytic aging conditions were found to be more detrimental to the spruce wood samples. The samples that underwent hydrolytic aging demonstrated higher water uptake levels, lower viscoelastic properties, and lower thermal degradation temperatures than the samples that were subjected to freeze-thaw cycling.

Wood wool panels are widely used in the construction industry as sustainable cementitious composites, but there is a growing need to replace traditional Portland cement with a binder that has a lower embodied carbon footprint. In addition, the sustainability of these panels may face serious impediments if the required amount of wood for their production needs a harvest rate higher than the rate at which the tree sources reach maturity. One solution is to use the wooden part of fast-growing plants such as hemp. However, the compounds extracted from the mixture of plants and water are the main cause of the delay observed during the hydration process of hydraulic binders in these cementitious composites. The objective of this study is to evaluate the effect of bio-aggregate lixiviates (hemp hurd) on the hydration kinetics of calcium sulfoaluminate (CSA) cement as a low-embodied-carbon alternative to ordinary Portland cement (OPC). The isothermal calorimeter showed that the hemp hurd lixiviate caused a greater delay in GU’s hydration process than CSA’s. At a 5% concentration, the main hydration peak for GU cement emerged after 91 h, whereas for CSA cement, it appeared much earlier, at 2.5 h. XRD and TGA analysis showed that after 12 h of hydration, hydration products such as calcium silicate hydrates (C-S-H) and portlandite (CH) were not able to form on GU cement, indicating low hydration of silicate products. Moreover, at 5% concentration, the carbonation of ettringite was observed in CSA cement. The compressive strength values obtained from the mixes containing hemp hurd lixiviate consistently showed lower values compared to the reference samples prepared with distilled water. Furthermore, the CSA samples demonstrated superior compressive strength when compared to the GU samples. After 28 days of hydration, the compressive strength values for CSA cement were 36.7%, 63.5% and 71% higher than GU cement at a concentration of 0.5%, 2% and 5% hemp hurd lixiviate, respectively.